Bronze Casting

Bronze sculpting involves making an original terracotta, plaster or wax model over an armature. From this a silicon rubber mould is made, forming a negative of the original. From the mould a hollow wax positive is cast. To this a series of wax runners and risers are fitted, these allow the molten bronze to flow in and the gases to come out. Once the wax is 'sprued up' it is coated inside and out with ceramic liquid which is built up in layers to form a strong heat resistant shell around the wax.

This is then baked upside down in an oven allowing the wax to melt out, hence the term 'cire perdue' or lost wax. Into the space left by the wax, molten bronze is poured at a temperature of 1200’c. Silver, gold, cast iron, stainless steel, lead and aluminium are other metals that can be cast using this method.

When the bronze has cooled the ceramic shell is chipped away and the sprues cut off. To remove the ceramic from the surface detail the bronze is placed in acid, which eats away the silica in the ceramic.

If the bronze has been cast in several pieces it is now welded together and chased. This is a highly skilled process recreating any surface detail.

The sculpture is now ready to be heated up and applied with various chemicals, which form the finished patina.